U.S. patent application number 10/919180 was filed with the patent office on 2006-02-16 for compliant thermal cap for an electronic device.
This patent application is currently assigned to International Business Machines Corporation. Invention is credited to Mark D. Schultz.
Application Number | 20060034060 10/919180 |
Document ID | / |
Family ID | 35799735 |
Filed Date | 2006-02-16 |
United States Patent
Application |
20060034060 |
Kind Code |
A1 |
Schultz; Mark D. |
February 16, 2006 |
Compliant thermal cap for an electronic device
Abstract
A cooling structure for an electronic device comprises a
compliant cap preloaded over the electronic device. The compliant
cap comprises a horizontal top surface and at least one vertical
support for the surface, the vertical support comprising a
compliant portion and wherein the compliant cap comprises a
thermally conducting material.
Inventors: |
Schultz; Mark D.; (Ossining,
NY) |
Correspondence
Address: |
MICHAEL J. BUCHENHORNER, ESQ;HOLLAND & KNIGHT
701 BRICKELL AVENUE
MIAMI
FL
33131
US
|
Assignee: |
International Business Machines
Corporation
|
Family ID: |
35799735 |
Appl. No.: |
10/919180 |
Filed: |
August 16, 2004 |
Current U.S.
Class: |
361/719 ;
257/E23.084; 257/E23.104; 257/E23.181 |
Current CPC
Class: |
H01L 23/3675 20130101;
H01L 2924/0002 20130101; H01L 2924/00 20130101; H01L 23/04
20130101; H01L 2924/0002 20130101; H01L 23/4006 20130101 |
Class at
Publication: |
361/719 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Claims
1. A cooling structure for an electronic device comprising: a
compliant cap preloaded over the electronic device; wherein the
compliant cap comprises a horizontal top surface and at least one
vertical support for the surface, the vertical support comprising a
compliant portion and wherein the compliant cap comprises a
thermally conducting material.
2. The system of claim 1, wherein the horizontal top surface
comprises a top plate comprising thinned edges.
3. The system of claim 1, wherein the compliant cap comprises a
first material having high thermal conductivity and a second
material comprising compliant properties.
4. The system of claim 1 further comprising a coupling element
disposed between the electronic device and the thermal cap.
5. The system of claim 1 wherein the thermal cap comprises a
serpentine structure continuously disposed along an edge of the
vertical support.
6. The system of claim 1 further comprising pins inserted into
holes in the compliant cap to provide the preloading.
7. The system of claim 1 wherein the electronic device is placed on
a substrate and the cooling structure further comprises fasteners
through the substrate.
8. The system of claim 1 further comprising a thermal interface
material applied between the electronic device and the thermal
cap.
9. The system of claim 8 further comprising a spreader located over
the electronic device and coupled with the thermal cap.
10. The system of claim 8 further comprising stops at corners of
the chip spreader interface for containing the thermal interface
material.
11. A method comprising the steps of: placing an electronic circuit
on a substrate; preloading a compliant cap over the electronic
device; wherein the compliant cap comprises compliant properties
and heat conducting properties.
12. The method of claim 11 further comprising applying a thermal
interface material between the electronic device and the thermal
cap.
13. The method of claim 11 further comprising applying a spreader
over the electronic device for coupling with the thermal cap.
14. The method of claim 11 further comprising including a coupling
element between the electronic device and the thermal cap.
15. The method of claim 11 further comprising inserting pins into
holes in the compliant cap to provide the preloading.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED-RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
[0003] Not Applicable.
FIELD OF THE INVENTION
[0004] The invention disclosed broadly relates to the field of
electronic devices and more particularly relates to the field of
thermal caps for electronic devices.
BACKGROUND OF THE INVENTION
[0005] During the normal operation of a computer, integrated
circuit devices generate significant amounts of heat. This heat
must be continuously removed, or the integrated circuit device may
overheat, resulting in damage to the device and/or a reduction in
operating performance. Cooling devices, such as heat sinks, have
been used in conjunction with integrated circuit devices in order
to avoid such overheating. Generally, a passive heat sink in
combination with a system fan has provided a relatively
cost-effective cooling solution. In recent years, however, the
power of integrated circuit devices has increased exponentially,
resulting in a significant increase in the amount of heat generated
by these devices, thereby making it extremely difficult to extract
heat form these devices.
[0006] Heat is typically extracted by coupling a heat spreader and
a thermal cap to the electronic device as a heat sink. Heat sinks
operate by conducting heat from a processor to the heat sink and
then radiating it into the air. The better the transfer of heat
between the two surfaces (the processor and the heat sink metal)
the better the cooling. Some processors come with heat sinks
attached to them directly, or are interfaced through a thin and
soft layer of thermal paste, ensuring a good transfer of heat
between the processor and the heat sink. The thermal paste serves
not only to transfer heat but to provide some degree of mechanical
compliance to compensate for dimensional changes driven by the high
operating temperatures of the devices. However, the paste is a weak
link in the thermal path. Attempts to thin this layer have resulted
in failure of the layer when it is exposed to dimensional changes.
There are some known mechanically complaint solutions but these
solutions still rely on paste film somewhere in the path. Thus
there is a need for a solution that overcomes these
shortcomings.
SUMMARY OF THE INVENTION
[0007] Briefly according to an embodiment of the invention a
cooling structure for an electronic device comprises a compliant
cap preloaded over the electronic device. The compliant cap
comprises a horizontal top surface and at least one vertical
support for the surface, the vertical support comprising a
compliant portion and wherein the compliant cap comprises a
thermally conducting material. In another embodiment of the present
invention, the horizontal top surface comprises a top plate
comprising thinned edges and the compliant cap comprises a first
material having high thermal conductivity and a second material
comprising compliant properties.
[0008] In yet another embodiment of the present invention, a method
for cooling an electronic device comprises placing an electronic
circuit on a substrate and preloading a compliant cap over the
electronic device. The compliant cap comprises compliant properties
and heat conducting properties. In yet another embodiment of the
present invention, the method further comprises applying a thermal
interface material such as a paste between the electronic device
and the thermal cap and applying a spreader over the electronic
device for coupling with the thermal cap.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The subject matter, which is regarded as the invention, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features and also the advantages of the invention will be apparent
from the following detailed description taken in conjunction with
the accompanying drawings. Additionally, the left-most digit of a
reference number identifies the drawing in which the reference
number first appears.
[0010] FIG. 1 shows a compliant thermal cap according to an
embodiment of the invention.
[0011] FIG. 1A shows a top view of the cooling structure of FIG.
1.
[0012] FIG. 2 shows a compliant thermal cap according to an
alternate embodiment of the invention.
[0013] FIG. 2A shows a top view of the cooling structure of FIG.
2.
[0014] FIG. 3 shows a preload scheme for a thermal cap according to
another embodiment of the invention.
[0015] FIG. 4 shows another preload scheme for a thermal cap
according to another embodiment of the invention.
[0016] FIG. 5 shows another preload scheme for a thermal cap
according to another embodiment of the invention.
[0017] FIG. 6 is a high level block diagram showing an information
processing system useful for implementing one embodiment of the
present invention.
DETAILED DESCRIPTION
[0018] FIG. 1 shows a cross sectional side view of a cooling
structure 100 for an electronic device 108. A compliant thermal cap
102 comprises a serpentine portion 104 for providing the resilience
required to overcome the problems of the prior art. The electronic
device (e.g., a semiconductor chip) 108, situated on a circuit
board 106, is connected by a coupling layer 110 comprising a
thermal paste, adhesive, or other thermal interface material. The
cap 102 serves the function of dissipating heat generated by the
electronic device 108 and has compliance in the "z" direction to
conform to thermal expansion by the device 108 and its substrate
materials caused by the difference in the coefficients of thermal
expansions of the materials of the device 108 and its substrate
materials and the cap 102. FIG. 1A shows a top view of the cooling
structure 100. The device 108 is shown in broken lines.
[0019] FIG. 2 shows a cooling structure 200 comprising a compliant
thermal cap 202 according to an alternate embodiment of the
invention. The compliant thermal cap 202 comprises a top plate (a
horizontal top surface) 203 having thinned edges 206 that provide
the required compliance to accommodate the vertical (z direction)
movement cause by thermal (temperature) variations in the operation
of the device 204. The compliant cap 202 also comprises a vertical
support member 205. A thermally-conductive layer 208 attaches the
device 204 to the top plate 203.
[0020] FIG. 2A is a top view of the cooling structure 200 shown in
FIG. 2. The thermal cap 202 is shown, as well as an outline of the
thinned edges 206 and the inner section of the top plate 203.
[0021] FIG. 3 shows a preload scheme for a thermal cap according to
a to another embodiment of the invention. The compliant cap 300 is
preloaded so that the compliance of the cap maintains contact
between the device and the cap 300, which is situated on a circuit
board 304. The preload is accomplished by inserting pins 308 and
310 into holes in the cap 300.
[0022] FIG. 4 shows another preload scheme for a compliant thermal
cap 400 comprising a serpentine compliant part 402 according to
another embodiment of the invention. Members 404, 406, and 408 are
temporarily attached to the cap, via connecting members 410 and
412, in order to provide preload while the cap is attached to the
system. These members would be removed after the attachment was
complete.
[0023] FIG. 5 shows another preload scheme for a thermal cap 502
according to a to another embodiment of the invention. The device
508 is shown within the cap with the resilience preloaded (note the
position of the thinned portions 504). The fasteners or screws 512
and 514 are inserted through the substrate or circuit board 506 to
attach it to the cap 502. Additional compliance can be introduced
by using a compliant material for the attachment layer 510.
[0024] The present invention can be utilized for cooling any of a
variety of electronic devices. In one embodiment of the present
invention, the present invention is used to cool a microprocessor
of an information processing system such as a computer. FIG. 6 is a
high level block diagram showing an information processing system
useful for implementing one embodiment of the present invention.
The computer system includes one or more processors, such as
processor 604. The processor 604 is connected to a communication
infrastructure 602. Various software embodiments are described in
terms of this exemplary computer system. After reading this
description, it will become apparent to a person of ordinary skill
in the relevant art(s) how to implement the invention using other
computer systems and/or computer architectures.
[0025] The computer system can include a display interface 608 that
forwards graphics, text, and other data from the communication
infrastructure 602 for display on the display unit 610. The
computer system also includes a main memory 606, preferably random
access memory (RAM), and may also include a secondary memory 612.
The secondary memory 612 may include, for example, a hard disk
drive 614 and/or a removable storage drive 616, representing a
floppy disk drive, a magnetic tape drive, an optical disk drive,
etc. The removable storage drive 616 reads from and/or writes to a
removable storage unit 618 in a manner well known to those having
ordinary skill in the art. Removable storage unit 618, represents a
floppy disk, a compact disc, magnetic tape, optical disk, etc.
which is read by and written to by removable storage drive 616. As
will be appreciated, the removable storage unit 618 includes a
computer readable medium having stored therein computer software
and/or data.
[0026] In alternative embodiments, the secondary memory 612 may
include other similar means for allowing computer programs or other
instructions to be loaded into the computer system. Such means may
include, for example, a removable storage unit 622 and an interface
620. Examples of such may include a program cartridge and cartridge
interface, a removable memory chip (such as an EPROM, or PROM) and
associated socket, and other removable storage units 622 and
interfaces 620 which allow software and data to be transferred from
the removable storage unit 622 to the computer system.
[0027] The computer system may also include a communications
interface 624. Communications interface 624 allows software and
data to be transferred between the computer system and external
devices. Examples of communications interface 624 may include a
modem, a network interface (such as an Ethernet card), a
communications port, a PCMCIA slot and card, etc. Software and data
transferred via communications interface 624 are in the form of
signals which may be, for example, electronic, electromagnetic,
optical, or other signals capable of being received by
communications interface 624. These signals are provided to
communications interface 624 via a communications path (i.e.,
channel) 626. This channel 626 carries signals and may be
implemented using wire or cable, fiber optics, a phone line, a
cellular phone link, an RF link, and/or other communications
channels.
[0028] In this document, the terms "computer program medium,"
"computer usable medium," and "computer readable medium" are used
to generally refer to media such as main memory 606 and secondary
memory 612, removable storage drive 616, a hard disk installed in
hard disk drive 614, and signals. These computer program products
are means for providing software to the computer system. The
computer readable medium allows the computer system to read data,
instructions, messages or message packets, and other computer
readable information from the computer readable medium. The
computer readable medium, for example, may include non-volatile
memory, such as a floppy disk, ROM, flash memory, disk drive
memory, a CD-ROM, and other permanent storage. It is useful, for
example, for transporting information, such as data and computer
instructions, between computer systems. Furthermore, the computer
readable medium may comprise computer readable information in a
transitory state medium such as a network link and/or a network
interface, including a wired network or a wireless network, that
allow a computer to read such computer readable information.
[0029] Computer programs (also called computer control logic) are
stored in main memory 606 and/or secondary memory 612. Computer
programs may also be received via communications interface 624. In
particular, the computer programs, when executed, enable the
processor 604 to perform the features of the computer system.
Accordingly, such computer programs represent controllers of the
computer system.
[0030] What has been shown and discussed is a highly-simplified
depiction of a programmable computer apparatus. Those skilled in
the art will appreciate that other low-level components and
connections are required in any practical application of a computer
apparatus.
[0031] Therefore, while there has been described what is presently
considered to be the preferred embodiment, it will be understood by
those skilled in the art that other modifications can be made
within the spirit of the invention.
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